The title of the series is Your Lie in April (Japanese: Shigatsu wa Kimi no Uso).
What was the lie? What was the reason for the lie?
The title of the series is Your Lie in April (Japanese: Shigatsu wa Kimi no Uso).
What was the lie? What was the reason for the lie?
I believe the lie was that Kaori lied about being in love with Watari.
On page 13 of Chapter 44. She says in her letter "This lie was that Miyazono Kaori had feelings for Watari Ryouta". She was secretly in love with Arima but didn't want to break the relationships between Arima and Tsubaki.
The real lie is that she never got to play with him again. As a child, she fell in love with him when she saw him play, and her dream was to one day stand by his side and play along with him. She managed to achieve her dream and play on the same stage along with him. After that she promised to do it again with him, but she died before it could happen.